Isoliquiritigenin Decreases Bone Resorption and Osteoclast Differentiation.

SCOPE: A dose-ranging study is performed using young estrogen-depleted rats to determine whether dietary isoliquiritigenin (ILQ) alters bone metabolism and if the effects are associated with estrogen receptor signaling. METHODS AND RESULTS: Six-week-old rats (ovariectomized at 4 weeks of age) are fed diets containing 0, 100, 250, or 750 ppm ILQ (n = 5/treatment) for 7 days. Gene expression in femur and uterus, blood markers of bone turnover, body composition, and uterine weight and epithelial cell height are determined. Because ILQ lowers bone resorption, the effect of ILQ on in vitro differentiation of osteoclasts from bone marrow of mice is assessed. Treatment resulted in a dose-dependent increases in serum ILQ but no changes in serum osteocalcin, a marker of global bone formation. Contrastingly, ILQ administration results in reduced serum CTX-1, a marker of global bone resorption, and reduces tartrate resistant acid phosphatase expression in osteoclast culture. ILQ treatment and endogenous estrogen production had limited overlap on gene expression in femur and uterus. However, uterine epithelial cell hyperplasia is observed in two of five animals treated with 750 ppm. CONCLUSIONS: In conclusion, dietary ILQ reduces bone resorption in vivo and osteoclast differentiation in vitro, by mechanisms likely differing from actions of ovarian hormones.

Reduction by, ligand exchange among, and covalent binding to glutathione and cellular thiols link metabolism and disposition of dietary arsenic species with toxicity.

Arsenic (As) is a common contaminant in the earth's crust and widely distributed in food and drinking water. As exposures have been associated with human disease, including cancer, diabetes, lung and cardiovascular disorders, and there is accumulating evidence that early life exposures are important in the etiology. Mode-of-action analysis includes a critical role for metabolic activation of As species to reactive trivalent intermediates that disrupt cellular regulatory systems by covalent binding to thiol groups. The central role of glutathione (GSH) in the chemical reactions of metabolism and disposition of arsenic species was investigated here. The chemical kinetics were measured for reactions in which GSH is a ligand for trivalent As complex formation, a reductant for pentavalent As species, and a participant in ligand exchange reactions with other biological As-thiol complexes. The diverse reactions of GSH with As species demonstrate prominent roles in: (1) metabolic activation via reduction; (2) transport from tissues that are the primary sources of reactive trivalent As intermediates following ingestion (intestine and liver) to downstream target organs (e.g., lung, kidney, and bladder); and (3) oxidation to the terminal metabolite, dimethylarsinic acid (DMAV), which is excreted. Studies of As metabolism and disposition emphasize the link between metabolic activation vs. excretion of As (i.e., internal dosimetry of reactive species) and the disruption of critical cellular thiol-based regulatory processes that define the dose-response characteristics of disease in human epidemiological studies and animal models and underpin risk assessment.

(±)-Equol does not interact with genistein on estrogen-dependent breast tumor growth.

Equol (EQ) is a prominent microbial metabolite of the soy isoflavone, daidzein, with estrogen-like properties. The major soy isoflavone, genistein (GEN), stimulated growth of estrogen-dependent breast cancer (EDBC) cells in vitro and tumor growth in vivo but EQ did not. To understand possible interactions of EQ and GEN on EDBC, EQ was used with GEN in combination in vitro and in vivo. Effects of EQ, GEN and EQ + GEN were evaluated using MCF-7 and T47D EDBC. Ovariectomized athymic mice were used as a model for in vivo tumor growth. Dietary EQ had no effect on MCF-7 tumor growth and the absence of effect was confirmed using a T47D EDBC in vivo model. EQ alone or in combination with GEN increased EDBC cell proliferation in vitro. EQ alone neither stimulated EDBC tumor growth in vivo at various doses nor suppressed tumor growth induced by dietary GEN. In summary, EQ has similar estrogenic effect as GEN in vitro but does not interact with GEN on EDBC tumor growth. Based on the evidence presented here, dietary EQ is unlikely to have estrogenic effects in vivo.

Metabolism and disposition of arsenic species from controlled dosing with sodium arsenite in adult and neonatal rhesus monkeys. VI. Toxicokinetic studies following oral administration.

Arsenic is a common toxic contaminant in food and drinking water. Metabolic activation of arsenic species produces reactive trivalent intermediates that can disrupt cellular regulatory systems by covalent binding to thiol groups. Arsenic exposures have been associated with human diseases including cancer, diabetes, lung and cardiovascular disorders and there is accumulating evidence that early life exposures are important in the etiology. Previous toxicokinetic studies of arsenite ingestion in neonatal CD-1 mice showed consistent evidence for metabolic and physiologic immaturity that led to elevated internal exposures to trivalent arsenic species in the youngest mice, relative to adults. The current study in rhesus monkeys showed that metabolism and binding of trivalent intermediates after arsenite ingestion were similar between adult monkeys and CD-1 mice. Unlike neonatal mice, monkeys from the age of 5-70 days showed similar metabolism and binding profiles, which were also similar to those in adults. The absence of evidence for metabolic immaturity in monkeys suggests that toxicological effects observed in mice from early postnatal exposures to arsenic could over-predict those possible in primates, based on significantly higher internal exposures.

A single or short time repeated arsenic oral exposure in mice impacts mRNA expression for signaling and immunity related genes in the gut.

Arsenic is prevalent in contaminated drinking water and affects more than 140 million people in 50 countries. While the wide-ranging effects of arsenic on neurological development and cancer draw the majority of concern, arsenic's effects on the gut mucosa-associated immune system are often overlooked. In this study, we show that 24 h after a single dose [low dose (50 µg/kg bw), medium dose (100 µg/kg bw) or high dose (200 µg/kg bw)] of arsenic by oral gavage, mice show significantly reduced gut mucosa-associated mRNA expression for the key genes involved in the signaling pathways central to immune responses, such as Nuclear factor κB (NFκB), Extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), p38 and Myeloid differentiation protein 88-dependent (Myd88) pathways. Additionally, mRNA expression of apoptosis, inflammasomes and inflammatory response genes are significantly downregulated in the animals exposed to arsenic. Comparisons of time-dependent effects (24 h vs 48 h) from low dose arsenic exposed animals showed a significant shift in expression of Myd88 alone, suggesting that the down regulation was sustained for the key genes/signaling pathway. An extended eight-day exposure to arsenic showed a decreased state of immune preparedness, though not as diminished as seen in the single dose exposure.

Metabolism and disposition of arsenic species from controlled dosing with dimethylarsinic acid (DMAV) in adult female CD-1 mice. V. Toxicokinetic studies following oral and intravenous administration.

Arsenic species contaminate food and water, with typical dietary intake below 1 µg/kg bw/d. Exposure to arsenic in heavily contaminated drinking water is associated with human diseases, including cardiovascular and respiratory disorders, diabetes, and cancer. Dietary intake assessments show that rice and seafood are the primary contributors to intake of both inorganic arsenic and dimethylarsinic acid (DMAV) and at similar magnitudes. DMAV plays a central role in the toxicology of arsenic because enzymatic methylation of arsenite produces DMAV as the predominant metabolite, which may promote urinary clearance but also generates reactive intermediates, predominantly DMAIII, that bind extensively to cellular thiols. Both inorganic arsenic and DMAV are carcinogenic in chronically exposed rodents. This study measured pentavalent and trivalent arsenic species in blood and tissues after oral and intravenous administration of DMAV (50 µg As/kg bw). DMAV underwent extensive first-pass metabolism in the intestine and liver, exclusively by reduction to DMAIII, which bound extensively to blood and tissues. The results confirm a role for methylation-independent reductive metabolism in producing fluxes of DMAIII that presumably underlie arsenic toxicity and indicate the need to include all dietary intake of inorganic arsenic and DMAV in risk assessments.

Comparative estrogenicity of endogenous, environmental and dietary estrogens in pregnant women II: Total estrogenicity calculations accounting for competitive protein and receptor binding and potency.

Evaluating the biological significance of human-relevant exposures to environmental estrogens involves assessing the individual and total estrogenicity of endogenous and exogenous estrogens found in serum, for example from biomonitoring studies. We developed a method for this assessment by integrating approaches for (i) measuring total hormone concentrations by mass spectrometry (Fleck et al., 2018), (ii) calculating hormone bioavailable concentrations in serum and, (iii) solving multiple equilibria between estrogenic ligands and receptors, and (iv) quantitatively describing key elements of estrogen potency. The approach was applied to endogenous (E1, E2, E3, E4), environmental (BPA), and dietary Genistein (GEN), Daidzein (DDZ) estrogens measured in the serum of thirty pregnant women. Fractional receptor occupancy (FRO) based estrogenicity was dominated by E1, E2 and E3 (ER-α, 94.4-99.2% (median: 97.3%), ER-ß, 82.7-97.7% (median: 92.8%), as was the total response (TR), which included ligand specific differences in recruitment of co-activator proteins (RCA). The median FRO for BPA was at least five orders of magnitude lower than E1, E2 and E3, and three orders of magnitude lower than the fetal derived E4 and GEN and DDZ. BPA contributed less than 1/1000th of the normal daily variability in total serum estrogenicity in this cohort of pregnant women.

Metabolism and disposition of arsenic species from oral dosing with sodium arsenite in neonatal CD-1 mice. IV. Toxicokinetics following gavage administration and lactational transfer.

Arsenic is a ubiquitous contaminant, with typical human dietary intake below 1 µg/kg bw/d and extreme drinking water exposures up to ∼50 µg/kg bw/d. The formation and binding of trivalent metabolites are central to arsenic toxicity and strong human evidence suggests special concern for early life exposures in the etiology of adult diseases, especially cancer. This study measured the metabolism and disposition of arsenite in neonatal mice to understand the role of maturation in metabolic activation and detoxification of arsenic. Many age-related differences were observed after gavage administration of arsenite, with consistent evidence in blood and tissues for higher exposures to trivalent arsenic species in neonatal mice related to the immaturity of metabolic and/or excretory functions. The evidence for greater tissue binding of arsenic species in young mice is consistent with enhanced susceptibility to toxicity based on metabolic and toxicokinetic differences alone. Lactational transfer from arsenite-dosed dams to suckling mice was minimal, based on no dosing-related changes in the levels of arsenic species in pup blood or milk collected from the dams. Animal models evaluating whole-life exposure to inorganic arsenic must use direct dosing in early neonatal life to predict accurately potential toxicity from early life exposures in children.

Licorice root components mimic estrogens in an object location task but not an object recognition task.

This study investigated the efficacy of components of licorice root to alter performance on two different recognition tasks, a hippocampus-sensitive metric change in object location (MCOL) task and a striatum-sensitive double object recognition (DOR) task. Isoliquiritigenin (ISL), licorice root extract (LRE), and whole licorice root powder (LRP) were assessed. Young adult female rats were ovariectomized (OVX) and exposed to ISL, LRE or LRP at 0.075%, 0.5% or 5% respectively in the diet. An estradiol group was included as a positive control based on our prior findings. Rats were allowed to explore two objects for three 5-min study trials (separated by 3-min intervals) before a fourth 5-min test trial where the objects were moved closer together (MCOL task) or replaced with two new objects (DOR task). Rats typically habituate to the objects across the three study trials. An increase in object exploration time in the test trial suggests the rat detected the change. Estradiol improved MCOL performance and impaired DOR performance, similar to previously shown effects of estradiol and other estrogens, which tend to improve learning and memory on hippocampus-sensitive tasks and impair striatum-sensitive cognition. LRP had no effect on recognition while exposure to ISL and LRE improved MCOL performance. Exposure to ISL, LRE and LRP failed to attenuate DOR, contrary to effects of estradiol shown here and to previous reports in young-adult OVX rats. These findings suggest components of licorice root may prove to be effective therapies targeting memory enhancement without unintended deleterious cognitive effects.

Metabolism and disposition of arsenic species after repeated oral dosing with sodium arsenite in drinking water. II. Measurements in pregnant and fetal CD-1 mice.

Arsenic is ubiquitous in the earth's crust, and human diseases are linked with exposures that are similar to dietary intake estimates. Metabolic methylation of inorganic arsenic facilitates excretion of pentavalent metabolites and decreases acute toxicity; however, tissue binding of trivalent arsenic intermediates is evidence for concomitant metabolic activation. Pregnant and fetal CD-1 mice comprise a key animal model for arsenic carcinogenesis since adult-only exposures have minimal effects. This study evaluated inorganic arsenic and its metabolites in pentavalent and trivalent states in blood and tissues from maternal and fetal CD-1 mice after repeated administration of arsenite through drinking water. After 8 days of exposure, DMA species were ubiquitous in dams and fetuses. Despite the presence of MMAIII in dams, none was observed in any fetal sample. This difference may be important in assessing fetal susceptibility to arsenic toxicity because MMA production has been linked with human disease. Binding of DMAIII in fetal tissues provided evidence for metabolic activation, although the role for such binding in arsenic toxicity is unclear. This study provides links between administered dose, metabolism, and internal exposures from a key animal model of arsenic toxicity to better understand risks from human exposure to environmental arsenic.

Comparative estrogenicity of endogenous, environmental and dietary estrogens in pregnant women I: Serum levels, variability and the basis for urinary biomonitoring of serum estrogenicity.

Biomonitoring of human exposure to estrogens most frequently focuses on environmental and dietary estrogens, and infrequently includes measures of exposure to potent endogenous estrogens present in serum. Pregnancy is a developmentally sensitive period during which "added" serum estrogenicity exceeding normal intra-individual daily variability may be of particular relevance. We made repeated measurements of serum concentrations of estrone (E1), estradiol (E2), estriol (E3), estetrol (E4), daidzein (DDZ), genistein (GEN) and bisphenol A (BPA) in thirty pregnant women using ultra-performance liquid chromatography coupled with tandem mass spectrometry detection (UPLC-MS/MS) and electrospray ionization (ESI). Serum E1, E2, and E3 concentrations varied significantly (coefficients of variation 9-10%) with broad ranges across the cohort: 1.61-85.1 nM, 9.09-69.7 nM, and 1.5-36.3 nM respectively. BPA (undetected, estimated from total exposure), DDZ and GEN concentrations were 1-5 orders of magnitude lower. The 24-h urinary elimination profiles of endogenous estrogens were each strongly correlated with their corresponding serum concentrations (Pearson's Correlation Coefficients of 0.83 (E1), 0.84 (E2) and 0.94 (E3)). A multivariate regression analysis produced equations for estimating serum concentrations of E1, E2, E3, E4, GEN and DDZ from urinary elimination rates and gestation period, an important step towards non-invasive biomonitoring for assessment of "added" estrogenicity during pregnancy.

Cellular and Molecular Effects of Prolonged Low-Level Sodium Arsenite Exposure on Human Hepatic HepaRG Cells.

Inorganic arsenic is a human carcinogen associated with several types of cancers, including liver cancer. Inorganic arsenic has been postulated to target stem cells, causing their oncogenic transformation. This is proposed to be one of the key events in arsenic-associated carcinogenesis; however, the underlying mechanisms for this process remain largely unknown. To address this question, human hepatic HepaRG cells, at progenitor and differentiated states, were continuously treated with a noncytotoxic concentration of 1 µM sodium arsenite (NaAsO2). The HepaRG cells demonstrated active intracellular arsenite metabolism that shared important characteristic with primary human hepatocytes. Treatment of proliferating progenitor-like HepaRG cells with NaAsO2 inhibited their differentiation into mature hepatocyte-like cells, up-regulated genes involved in cell growth, proliferation, and survival, and down-regulated genes involved in cell death. In contrast, treatment of differentiated hepatocyte-like HepaRG cells with NaAsO2 resulted in enhanced cell death of mature hepatocyte-like cells, overexpression of cell death-related genes, and down-regulation of genes in the cell proliferation pathway, while biliary-like cells remained largely unaffected. Mechanistically, the cytotoxic effect of arsenic on mature hepatocyte-like HepaRG cells may be attributed to arsenic-induced dysregulation of cellular iron metabolism. The inhibitory effect of NaAsO2 on the differentiation of progenitor cells, the resistance of biliary-like cells to cell death, and the enhanced cell death of functional hepatocyte-like cells resulted in stem-cell activation. These effects favored the proliferation of liver progenitor cells that can serve as a source of initiation and driving force of arsenic-mediated liver carcinogenesis.

Metabolism and pharmacokinetics of zearalenone following oral and intravenous administration in juvenile female pigs.

Zearalenone (ZEN) is a well-studied mycotoxin whose potent estrogenic properties have been used by international regulatory bodies to set health-based guidance values for ZEN exposure in grain-based foods from changes in hormonally responsive tissues of juvenile female pigs. The role of metabolism in determining estrogenic responses in vivo is a major uncertainty in inter-species extrapolation to humans and in assessing the potential for added susceptibility in sensitive subpopulations. This study evaluated the metabolism of ZEN and pharmacokinetics in ∼2 month-old female pigs using oral and intravenous dosing. The absolute bioavailability (AUCoral/AUCIV) of receptor-active ZEN aglycone was 1.8 ± 0.80%, consistent with extensive pre-systemic Phase II conjugation. Reductive metabolism to α-zearalenol (α-ZEL) was extensive, with smaller amounts of ß-ZEL. When combined with its higher binding affinity, relative to ZEN and ß-ZEL, α-ZEL was the predominant contributor to total estrogen receptor ligand activity (∼90%) after oral dosing with ZEN. The apparent similarities of reductive and Phase II conjugation metabolism of ZEN between pigs and humans support the use of juvenile female pigs as a sensitive model for risk assessments of estrogenic effects from dietary ZEN.

Furan-induced transcriptomic and gene-specific DNA methylation changes in the livers of Fischer 344 rats in a 2-year carcinogenicity study.

Furan is a significant food contaminant and a potent hepatotoxicant and rodent liver carcinogen. The carcinogenic effect of furan has been attributed to genotoxic and non-genotoxic, including epigenetic, changes in the liver; however, the mechanisms of the furan-induced liver tumorigenicity are still unclear. The goal of the present study was to investigate the role of transcriptomic and epigenetic events in the development of hepatic lesions in Fischer (F344) rats induced by furan treatment in a classic 2-year rodent tumorigenicity bioassay. High-throughput whole-genome transcriptomic analysis demonstrated distinct alterations in gene expression in liver lesions induced in male F344 rats treated with 0.92 or 2.0 mg furan/kg body weight (bw)/day for 104 weeks. Compared to normal liver tissue, 1336 and 1541 genes were found to be differentially expressed in liver lesions in rats treated with 0.92 and 2.0 mg furan/kg bw/day, respectively, among which 1001 transcripts were differentially expressed at both doses. Pairing transcriptomic and next-generation bisulfite sequencing analyses of the common differentially expressed genes identified 42 CpG island-containing genes in which the methylation level was correlated inversely with gene expression. Forty-eight percent of these genes (20 genes, including Areg, Jag1, and Foxe1) that exhibited the most significant methylation and gene expression changes were involved in key pathways associated with different aspects of liver pathology. Our findings illustrate that gene-specific DNA methylation changes have functional consequences and may be an important component of furan hepatotoxicity and hepatocarcinogenicity.

Low dose assessment of the carcinogenicity of furan in male F344/N Nctr rats in a 2-year gavage study.

Furan is a volatile organic chemical that is a contaminant in many common foods. Furan is hepatocarcinogenic in mice and rats; however, the risk to humans from dietary exposure to furan cannot be estimated accurately because the lowest tested dose of furan in a 2-year bioassay in rats gave nearly a 100% incidence of cholangiocarcinoma. To provide bioassay data that can be used in preparing risk assessments, the carcinogenicity of furan was determined in male F344/N Nctr rats administered 0, 0.02, 0.044, 0.092, 0.2, 0.44, 0.92, and 2 mg furan/kg body weight (BW) by gavage 5 days/week for 2 years. Exposure to furan was associated with the development of malignant mesothelioma on membranes surrounding the epididymis and on the testicular tunics, with the increase being significant at 2 mg furan/kg BW. There was also a dose-related increase in the incidence of mononuclear cell leukemia, with the increase in incidence being significant at 0.092, 0.2, 0.92, and 2 mg furan/kg BW. Dose-related non-neoplastic liver lesions included cholangiofibrosis, mixed cell foci, basophilic foci, biliary tract hyperplasia, oval cell hyperplasia, regenerative hyperplasia, and cytoplasmic vacuolization. The most sensitive non-neoplastic lesion was cholangiofibrosis, the frequency of which increased significantly at 0.2 mg furan/kg BW.

Irreversible down-regulation of miR-375 in the livers of Fischer 344 rats after chronic furan exposure.

Furan, a rodent liver carcinogen, is a chemical contaminant found in a broad range of cooked foods. Despite a lack of conclusive evidence regarding furan genotoxicity, several reports indicate that furan induces a broad range of non-genotoxic alterations, including aberrant expression microRNAs (miRNAs). In order to clarify the role of miRNA alterations with respect to furan carcinogenicity, we investigated the expression of several cancer-related miRNAs in the livers of Fischer 344 rats treated continuously with furan. The results demonstrate that furan induced marked changes in miRNA expression, characterized by over-expression of hepatic miRNAs, miR-34a, miR-93, miR-200a, miR-200b, and miR-224, and down-regulation of miR-375. Interestingly, a majority of furan-induced miRNA changes diminished after the cessation of the furan treatment. In contrast, the expression of miR-375 steadily decreased in a time-dependent manner following furan treatment. The reduced expression of miR-375 was accompanied by cytosine DNA hypermethylation and increased lysine methylation of histone H3K9 and H3K27 at the MiR-375 gene. The significance of miR-375 inhibition with respect to the pathogenesis of furan-induced liver toxicity and carcinogenicity may be attributed to its role in the up-regulation of Yes-associated protein 1 (YAP1), which is one of the principal events in the liver carcinogenesis. The results of the present study support the hypothesis of the non-genotoxic mode of action of furan and emphasize the importance of epigenetic alterations in the mechanism of furan hepatotoxicity.

Urine and serum biomonitoring of exposure to environmental estrogens II: Soy isoflavones and zearalenone in pregnant women.

UNLABELLED: Urine and serum biomonitoring was used to measure internal exposure to selected dietary estrogens in a cohort of 30 pregnant women. Exposure was measured over a period comprising one-half day in the field (6 h) and one day in a clinic (24 h). Biomonitoring of the dietary phytoestrogens genistein (GEN), daidzein (DDZ) and equol (EQ), as well as the mycoestrogen, zearalenone (ZEN) and its congeners, was conducted using UPLC-MS/MS. Biomonitoring revealed evidence of internal exposure to naturally occurring dietary estrogens during pregnancy. Urinary concentrations of total GEN, DDZ and EQ were similar to levels reported for general adult U.S. POPULATION: Measurable concentrations of total (parent and metabolites) GEN, DDZ and EQ were present in 240, 207 and 2 of 270 serum samples, respectively. Six out of 30 subjects had measurable concentrations of unconjugated GEN and/or DDZ in serum between 0.6 and 7.1 nM. Urine to serum total isoflavone ratios for GEN, DDZ and EQ were 13, 47, and 180, respectively. ZEN and its reductive metabolite, α-zearalenol (α-ZEL), were present in pregnant women (11 out of 30 subjects) as conjugates at levels near the limit of quantification. The average total urinary concentration was 0.10 µg/L for ZEN and 0.11 µg/L for α-ZEL.

Effects of letrozole on breast cancer micro-metastatic tumor growth in bone and lung in mice inoculated with murine 4T1 cells.

Breast cancer (BC) is the leading cancer in women worldwide. Metastasis occurs in stage IV BC with bone and lung being common metastatic sites. Here we evaluate the effects of the aromatase inhibitor letrozole on BC micro-metastatic tumor growth in bone and lung metastasis in intact and ovariectomized (OVX) mice with murine estrogen receptor negative (ER-) BC cells inoculated in tibia. Forty-eight BALB/c mice were randomly assigned to one of four groups: OVX, OVX + Letrozole, Intact, and Intact + Letrozole, and injected with 4T1 cells intra-tibially. Letrozole was subcutaneously injected daily for 23 days at a dose of 1.75 µg/g body weight. Tumor progression was monitored by bioluminescence imaging (BLI). Following necropsy, inoculated tibiae were scanned via µCT and bone response to tumor was scored from 0 (no ectopic mineralization/osteolysis) to 5 (extensive ectopic mineralization/osteolysis). OVX mice had higher tibial pathology scores indicative of more extensive bone destruction than intact mice, irrespective of letrozole treatment. Letrozole decreased serum estradiol levels and reduced lung surface tumor numbers in intact animals. Furthermore, mice receiving letrozole had significantly fewer tumor colonies and fewer proliferative cells in the lung than OVX and intact controls based on H&E and Ki-67 staining, respectively. In conclusion, BC-inoculated OVX animals had higher tibia pathology scores than BC-inoculated intact animals and letrozole reduced BC metastases to lungs. These findings suggest that, by lowering systemic estrogen level and/or by interacting with the host organ, the aromatase inhibitor letrozole has the potential to reduce ER- BC metastasis to lung.

Licorice root components in dietary supplements are selective estrogen receptor modulators with a spectrum of estrogenic and anti-estrogenic activities.

Licorice root extracts are often consumed as botanical dietary supplements by menopausal women as a natural alternative to pharmaceutical hormone replacement therapy. In addition to their components liquiritigenin (Liq) and isoliquiritigenin (Iso-Liq), known to have estrogenic activity, licorice root extracts also contain a number of other flavonoids, isoflavonoids, and chalcones. We have investigated the estrogenic activity of 7 of these components, obtained from an extract of Glycyrrhiza glabra powder, namely Glabridin (L1), Calycosin (L2), Methoxychalcone (L3), Vestitol (L4), Glyasperin C (L5), Glycycoumarin (L6), and Glicoricone (L7), and compared them with Liq, Iso-Liq, and estradiol (E2). All components, including Liq and Iso-Liq, have low binding affinity for estrogen receptors (ERs). Their potency and efficacy in stimulating the expression of estrogen-regulated genes reveal that Liq and Iso-Liq and L2, L3, L4, and L6 are estrogen agonists. Interestingly, L3 and L4 have an efficacy nearly equivalent to E2 but with a potency ca. 10,000-fold less. The other components, L1, L5 and L7, acted as partial estrogen antagonists. All agonist activities were reversed by the antiestrogen, ICI 182,780, or by knockdown of ERα with siRNA, indicating that they are ER dependent. In HepG2 hepatoma cells stably expressing ERα, only Liq, Iso-Liq, and L3 stimulated estrogen-regulated gene expression, and in all cases gene stimulation did not occur in HepG2 cells lacking ERα. Collectively, these findings classify the components of licorice root extracts as low potency, mixed ER agonists and antagonists, having a character akin to that of selective estrogen receptor modulators or SERMs.

Dietary licorice root supplementation reduces diet-induced weight gain, lipid deposition, and hepatic steatosis in ovariectomized mice without stimulating reproductive tissues and mammary gland.

SCOPE: We studied the impact of dietary supplementation with licorice root components on diet-induced obesity, fat accumulation, and hepatic steatosis in ovariectomized C57BL/6 mice as a menopause model. MATERIALS AND METHODS: We evaluated the molecular and physiological effects of dietary licorice root administered to ovariectomized C57BL/6 mice as root powder (LRP), extracts (LRE), or isolated isoliquiritigenin (ILQ) on reproductive (uterus and mammary gland) and nonreproductive tissues important in regulating metabolism (liver, perigonadal, perirenal, mesenteric, and subcutaneous fat). Quantitative outcome measures including body weight, fat distribution (magnetic resonance imaging), food consumption, bone density and weight (Dual-energy X-ray absorptiometry), and gene expression were assessed by the degree of restoration to the preovariectomized health state. We characterized histological (H&E and oil red O staining) and molecular properties (expression of certain disease markers) of these tissues, and correlated these with metabolic phenotype as well as blood levels of bioactives. CONCLUSION: Although LRE and ILQ provided some benefit, LRP was the most effective in reducing body weight gain, overall fat deposition, liver steatosis, and expression of hepatic lipid synthesis genes following ovariectomy. Our data demonstrate that licorice root provided improvement of multiple metabolic parameters under conditions of low estrogen and high-fat diets without stimulating reproductive tissues.